Compressor valve for internal combustion engine



March 30, 1965 H. KosoFF 3,175,584

COMPRESSOR VALVE FOR INTERNAL COMBUSTION ENGINE Filed June 27, 1963 2 Sheets-Sheet 1 F Y a F E m w m m m v 5 56 M D A L O H 0C W. m 35cm 30 I T .m 3. ulufigwmv a! 0v EOE I 3 on 3. ll. l. ow u I .w A 8 w wv 2 l o t 2 Q \l ow v r 59;

+5253 x 35cm 30 March 30, 1965 H. KOSOFF 3,175,584

COMPRESSOR VALVE FOR INTERNAL COMBUSTION ENGINE Filed June 2'7, 1963 2 Sheets-Sheet 2 INVENTOR.

HAROLD KOSOFF HQQAME ATTORNEY United States Patent 3,175,584 COMPRESSOR VALVE FOR INTERNAL COMBUSTION ENGINE Harold Kosnff, 1203 Hale St., Philadelphia 11, Pa. Filed June 27, 1963, Ser. No. 291,067 7 Claims. (Cl. 137625.33)

This invention relates to an internal combustion engine of the type having a number of reciprocating pistons. In particular, it relates to, and has great utility, in free piston engines.

In my previous applications, Serial No. 76,933 filed December 19, 1960, now Patent No. 3,127,881, and Serial No. 169,311 filed January 29, 1962, now Patent No. 3,129,- 878, I described and claimed a new free piston engine having relatively few main parts and free from any mechanical synchronizing linkage between the pistons thereof. While that engine was, in general, highly satisfactory, it became apparent that it was possible to build an even more sophisticated and better engine which incorporated novel features.

It is therefore among the objects of this invention to provide:

(1) An internal combustion engine which includes means therein for minimizing the frictional losses of the pistons.

(2) An internal combustion engine with novel means for providing internal cooling.

(3) An internal combustion engine in which the crankcase and/ or compressor chamber are effectively isolated from the combustion chamber.

(4) An internal combustion engine which employs a novel, simple, and highly efficient compressor intake valve.

(5) An internal combustion engine with novel means for providing internal lubrication.

(6) A free piston engine with novel means for metering the fuel applied thereto.

(7) A free piston engine having novel cooling, lubricating and valve structures.

Other objects of the invention will occur to those skilled in the art upon perusal of the drawings, specification and claims herein.

In accordance with my invention I minimize frictional losses and thereby increase engine efficiency by reducing the surface area of contact of the pistons with the inner walls of the cylinder. I do this by undercutting the pistons, i.e., by making selected portions of them have smaller diameters than other portions thereof. In addition, I take advantage of this undercut portion by using it as a channel to which external air is applied under pressure for keeping down the temperature of the engine. This air also has the effect of removing any undesired combustion products that get by the rings and thus prevent other regions of the engine from becoming contaminated. Also, I use the changes in the air supply pressure caused by the piston head periodically blocking the air flow as a means for sensing the extent of outward piston stroke. Furthermore, instead of using conventional compressor intake valves that require a pressure differential to activate them, I employ a valve member, disposed around and actuated by the piston, which cooperates with an opening in the cylinder to permit external air to enter the compressor chamber upon the outstroke of the pistons and closes the opening on the instroke of the pistons. I also provide a novel system for lubricating the pistons by applying a lubricant via internal passageways therein.

FIGURE 1 is a fragmentary side elevation view, partly in section, of an internal combustion engine constructed in accordance with one form of my invention.

FIGUREv 2 is an enlarged sectional view of a portion of one piston in the region of the rings showing one part of the lubricating system therefor.

3,175,584 Patented Mar. 30, 1965 FIGURES 3 and 4 and, respectively, end and side elevation views, enlarged, of the compressor chamber intake valve shown in FIG. 1.

FIGURE 5 is a fragmentary enlarged view of the undercut rear piston packing depicted in FIG. 1.

FIGURE 6 is a fragmentary enlarged view of the undercut front piston packing depicted in FIG. 1.

Referring now to FIGURE 1 there is shown my novel internal combustion engine of the free-piston type which embodies the present invention. As in the engine described and claimed in the aforementioned co-pending patent application Serial No. 169,311, it consists of relatively few main parts. To conserve space and to simplify the explanation, little more than half of the entire engine has been shown since practically all of the structure thereof to the right of the mid point of the combustion chamber is identical with the structure to the left thereof. One exception is the fuel-metering system which, obviously, is associated only with the intake manifold.

Basically, engine 10 consists of two cylinders 11 and 12 having central narrow portions 11:: and 12a respectively which interfit a centrally located combustion block 9. Within the respective cylinders 11 and 12 are located reciprocating pistons 13 and 1 The narrow cylinder portions 11a and 12a also pass through central openings in substantially identical manifolds 15 and 17 and are constructed to mate with or interfit them snugly. While the manifolds 15 and 17 are structurally identical, the manifold 15 is used as the air-fuel intake manifold whereas the manifold 17 is used as the exhaust manifold.

There are two end caps at opposite ends of the cylinders, only one of which, end cap 19 is shown in this figure. A number of bolts 21, 22 are provided which may extend the entire length of the engine, passing through aligned apertures in the end caps and in the manifolds. Tension is provided by screwing nuts 16 at the ends of the long bolts thereby urging the end caps and the cylinders toward one another at the center so that the narrow portions 11a and 12a tightly interfit the combustion block openings. Nuts 18 are provided around the bolts 21 and 22 to urge the manifolds 15 and 17 outward so that their stepped central apertures snugly mate with similarly stepped outer surfaces of the cylinder portions 11a and 12a.

The end caps are provided with apertures such as aperture'19a which are located substantially centrally therein and through which is passed a bolt such as the bolt 23. The bolt 23 is connected to an elongated member 24 which has a square or other uncircular cross-section designed to fit a similarly cross-sectioned passageway 13a formed within the piston 13. It is the function of this member 24 and this passageway 13a to prevent rotation of the piston 13 about its longitudinal axis and thus, prevent the piston ring joint from snagging in the intake or exhaust ports.

In accordance un'th one feature of my invention, it will be noted that the frictional force produced by the reciprocation of the pistons 13 and 14 is reduced by providing undercut portions 13b and in the piston 13, and similar undercut portions in the piston 14 of which only the tons, so as to maintain closer synchronization in the novel free piston engine, the area of contact is minimized by extensive piston undercutting. As described below, this undercut also provides for a very efficient internal air cooling-system, and thus,- the undercut is very useful with all reciproacting internal combustion engines.

The internal air cooling system consists of applying, via pipe 26, air under pressure into spaces 20 and 25 bounded by part of the inside surface of the portion 11a and 12a, part of the outside surface of the narrow diameter portions 13c andl tc of the piston 13 and 14;, the inner end portion of the pistons which include the rings, and the novel compressor inlet valve 28. This air circulates around in the spaces 13c and 14c and is exhausted from the space 13c by means of the tube 31 and its counterpart (not shown) for the space 140. This cooling air may also be blown into the intake and exhaust manifolds. The

' pressurized air eliminates from the engine any combustion products that may leak past the rings.

This direct internal cooling system has a number of advantages over existing external cooling systems. Most known air-cooled engines require large fins, powerful fans, and a considerable amount of sheetmetal work in order to direct the cooling air around the exterior of the engine. Since the cooling is not directed to the point at which cooling is most needed, i.e., in the region where the piston rubs against the inner wall surface of the cylinder, these conventional systems are relatively ineflicient. Thus, if it is desired to keep the maximum internal engine temperature at about 400 Fahrenheit, for example, a 200 temperature drop through the cylinder and fins must be allowed for, and it is necessary to keep the external fins less than 200.

Using my direct cooling system, however there is no need for large fins, fans, or extensive sheetmetal work since all that is necessary is to provide an inlet for the air through a hole in the cylinder wall which communicates with the portion of the piston which has been undercut to reduce frictional losses. Since the cooling air of my system is applied directly to the surfaces that need to be cooled, the cooling air may undergo a temperature rise to 400 F. Under typical conditions, the external system cooling air may undergo a temperature rise from 70 to 200 (difference of 130), while the internal system cooling air may undergo a temperature rise from 70 to 400 (difference of 330). Assuming that the quantity of heat transferred is equal in both cases, the amount of air required for the external cooling system is 330/130 or about Zl/ztirnes the amount of air requiredby the internal cooling system. Additionally, the movement of the piston provides beneficial turbulence to the cooling air of the internal system.

Fuel metering system The bellows 35 is' mechanically coupled by a rigid link 36 to a fuel valev 37 to which fuel is applied via tube 38.

p The valve 33 smooths out the pressure applied in pulses to teh bellows 35 to a mean value. The valve 37 and the link 36 are so arranged that an increase in the pressure within the bellows 35 will move the link 36 in a direction such as to'decrease the amount of fuel applied via the intake manifold to the combustion chamber, and vice versa. In the intervals when the aperture 11b is not covered by the portion 13g, the pressure in tube 32 will be low relative to the pressure in bellows 35, and thus, air will flow from the bellows reducing the pressure therein.

As an example of its operation let it be assumed that the normal outstroke of the piston should be such that portion 13g covers one-half of the aperture 11b at its end. This would cause the average pressure in bellows 35 to be of some value, say 20 lbs. per square inch. If the outstroke exceeds this length it will cause perhaps threequarters of the aperture 11b to be covered so that pneumatic pulses of greater duration and amplitude are applied to bellows '35 increasing its average pressure to, say 21 pounds per square inch. This will move link 36 outward to decrease the fuel applied. Consequently, when the rebouncing pistons come together for the next combustion of fuel, there will be a smaller explosion so that the pistons will not travel outward so far. Hence, the piston portion 13g during the next few strokes will cover less than three-quarters of the aperture. If the outstroke, on the other hand, is less than normal it will cause perhaps one-quarter of the aperture 11b to be covered so that pneumatic pulses of shorter duration and amplitude are applied to bellows 35 thereby decreasing the average pressure therein to 19 pounds per square inch. This will cause the link 36 to move inwardly and increase the fuel rate whereupon the subsequent stronger explosions in the combustion chamber 8 will tend to lengthen the outstroke until it tends, on the average, to cover the predetermined half of the aperture.

Of course, other predetermined average outstroke positions may be effected by changing the location of the aperture 115, employing a different bellows, changing the pressure of the applied air, etc. The successful operation of this outstroke control system also assumes that the piston Will not ordinarily move so far out that its inner face will pass, totally or partially, the aperture 111:.

Compressor valve Another novel feature of my invention is my provision of a one piece, highly efiicient compressor chamber valve 28 shown magnified in FIGURES 3 and 4. Instead of being operated by a pressure difference, it is designed for much more efficient mechanical actuation. Valve 28 has a serrated lip 28a having cuts 280 therein. This lip is compressed to enable it to slip into the groove 11c formed in the inner wall of narrow cylinder portion 11a whereupon it resiliently expands to itsinormal shape. The lip 28a is locked into the groove '11:: by the undercut portion 13c of the piston. The inside diameter of the valve is made to have a sliding or frictional fit around the undercut portion 13c of the piston so that the valve will be moved inwandly and outwardlyv to a limited extent by the reciprocating piston. However, when the valve movement is limited, it will remain stationary and the piston will then slide against the valve. The valve inward movement is limited by the annular flange portion 28b bearing against an inside surface of the compressor chamber 40 and its outward movement is limited by the lip 28a contacting the left vertical side of the groove .110.

On the outstroke of .the'piston the valve is moved away from the compressor wall 40a .by the piston, thereby uncovering the inlet ports 42. This allows air to be'drawn into the compressor chamber. As the piston continues to move outward it slides against .the valve which remains motionless since it is constrained by the groove 110.

When the-piston startsto move inwardly, the valve 28 moves with it until the valve seats against the Wall 40a thereby sealing the sixteen'inlet ports 42. For theremainder of the in-s troke the valve stays motionless in its sealing position, while the piston slides against it.

This valve also acts as a flange packing which tends to prevent fuel-air mixture, exhaust products, cooling air, and blow-by combustion products from entering the compressor chamber 40. The valve 28 may be made from glass-filled Teflon. i

Lubrication system In order to minimize the friction and wear of the pistons and cylinders I have devised a novel lubrication system which applies oil to the ring area of the pistons by means of an internal passageway within the piston itself. Thus, pistons 13 and 14 have internal passageways 13d and 14d respectively. Connected to the passageway 13d toward the back of the piston is a rigid L-shaped tubular member 44 to which a flexible tubular member 45 is connected. The other end of the flexible member 45 is connected to another rigid tubular member 46 which is screwed or otherwise secured within an L-shaped passageway 47. Of course, an opening at other points along the cylinder wall could alternatively be used as the inlet for the oil.

Oil is applied to the passageway 47 by means of the duct 48. As shown in the enlarged view in FIGURE 2, the inner end of the passageway 13d has an L-shaped portion 13c which opens out into a circular groove 13 that is formed in the outside surface of the piston head 13g. This groove allows the oil to distribute itself evenly around the piston head: Most of the oil tends to be trapped in the region adjacent to the groove by the rings 13h on each side of the groove, assuring an adequate and continuous supply of oil for the rings and cylinder walls. A small amount of the oil may succeed in getting between the other rubbing surfaces of the piston and the adjacent interior cylinder walls.

Though not shown in FIG. 2, the region of the piston head between the first ring (closest to the combustion chamber) and the combustion chamber is preferably undercut sufiiciently to produce a clearance between it and the adjacent inner cylinder wall. This is done since oil in the groove 13 generally does not reach the surface portion 13m. The duct 31' also acts' as an oil drain and as an outlet for pressurized air from the cooling system. In addition, oil drains may also be formed within the manifolds 15 and 17.

Seals, packing, etc.

In order to cushion the end caps against impact by the pistons if the engine goes out of control, shock absorbers such as the absorber 48 may be fastened to the piston guidance members such as the member 24 as shown. The absorber 48 may be made of rubber or other suitable material.

A rear piston packing member 51 (FIG. 5) is provided which is pressed firmly inward by the annular threaded retaining member 52 that is screwed onto an intermediate threaded portion of the piston 13. Packing 51 has an undercut portion 51a that insures a good seal in the region of portion 51b by effectively increasing the force per unit area of the outer edge of portion 51b against the cylinder 11. Packing 51 has an annular recessed portion 51c which also aids in maintaining the portion 51b in intimate contact with the inside cylinder wall. This assists in isolating the rebounce chamber 41 from the compression or pump chamber 40.

A front piston packing member 50 (FIG. 6) is also provided which is screwed by screws 50d into the wider diameter portion of the piston. In order to provide a tight seal at the edge of portion 501) it also has an undercut portion 50a. It also includes an annular recess 50c which, by virtue of the air pressure in it, helps to increase the pressure of the seal at 5012 against the cylinder wall. By keeping these parts in intimate contact with one another the compression chamber 40 is kept isolated from the rebounce chamber. This front packing 50 also has a portion 50e shaped to act as a shock absorber should the engine go out of control. Both of the packings 50 and 51 may be of Teflon or other materials having similar properties.

While these seals are useful in many types of reciprocating piston engines, they are especially useful in the engine illustrated which employs the pneumatic synchronizing system to be briefly described below.

Synchronizing system As this system is not part of this invention and is shown only as part of one illustrative environment for my invention only a passing reference will be made thereto. Connected to each rebounce chamber is a duct such as duct 60 which passes through an aperture in the end cap 19. The duct is connected to a source (not shown) of a gas under pressure. A restriction such as a needle valve 69 is included along the duct. There is also a vent 61 which is located in the cylinder Wall approximately where the outer end of the piston 13 will be when it is near its maximum inward position.

As explained in detail in my co-pending application Serial No. 76,933, if the piston 13 begins to move inward too far at the end of its instroke, the outer edge of the packing 51 will pass over the inner opening of the passageway 61. Thus, to the extent that the internal opening of the passageway 61 is uncovered by the length of the inward stroke, the pressure in the rebounce chamber 41 (which is being continuously built up by the flow of gas through orifice 68) will be reduced. This occurs because the passageway 61 communicates via the duct 62, the valve 63 and the pipe 64 with a gas receiver which may be, for example, the ambient atmosphere. As a result of this pressure reduction in the rebounce chamber, the piston 13 will tend to have its instrokes in the next several cycles shortened with the result that the inner opening of the passageway 61 will not be exposed so much by the passage of the piston 13 past it. Consequently the pressure in the rebounce chamber 41 will continue to build up uninterruptedly resulting, after a time, in a tendency toward longer instrokes of the piston. Thus, over a period of time, the average position of the pistons will be stabilized Miscellaneous remarks In the particular engine shown in FIG. 1 but not constituting part of my engine is a starting system which consists of a substantially cylindrical cavity 65 formed in the combustion block 9. This cavity communicates with the combustion chamber itself by means of a passageway 66. A plug 67 is screwed into and out of the threaded aperture 65a to enable a starting explosive charge to be inserted into the cavity 65 and then, when the plug is screwed in, to channel the explosion into the combustion chamber 8 via the passageway 66. The plug 67 is provided with a longitudinal passageway into which a pin (not shown) may be fitted. Part of the pin protrudes outside the plug 67 and its other end is arranged to strike the charge so as to detonate it when the external end of the pin is struck sharply. The detonation of the charge produces a sudden expansion of the gases through the passageway 66 into the combustion chamber with a force sufficient to cause the pistons 13 and 14 to be immediately forced outward against the pressure in the rebounce chambers. The rebounce pressure will force the pistons inward toward one another thereby compressing the fuel and air mixture applied to the rebounce chamber through the inlet pipe 15a via the manifold 15. This compression will inaugurate the second and successive combustions of the fuel-air charge 'in the combustion chamber. The combustion chamber block 9 is preferably provided with annular fins 9a to help dissipate the heat generated within the combustion chamber.

I claim:

1. A valve for apparatus which has a cylinder-like means and a member arranged to move within said cylinder-like member, said valve comprising: means constructed and arranged to be moved by said member in the same directions as the latter, said means being contively exceeds said first and second predetermined distances.

2. The valve according to claim 1 wherein said means fits around said member, wherein said cylinder-like means has a selected number of apertures therein, and wherein said means is constructed and arranged .to move against said apertures when said member moves insaid one direction and to move away from said apertures when said member moves ,in said other direction.

7 3. The Valve according to claim 2 wherein said means has a projecting portion and wherein said cylinder-like means has a recessed portion in its internal surface constructed to be engaged by said projection, said recessed portion and saidprojection cooperating to limit the movement of said means to saidsecond predetermined distance when said member cmovs in said other direction. 7

4. The valve according to-claim -3 wherein said member is a piston which reciprocates, wherein said apertures are disposed so that their axes are parallel to the axis of reciprocation of said piston, and wherein said valve means has an annular flange portion extending transversely of said axis of reciprocation, said. apertures and said flange portion being arranged so that when said valve means is moved inwardly by said pistonsaid flanged portion is pressed against said apertures.

5. A valve for an engine whichhas at least one cylinder member therein with an aperture in a wall thereof and also has at least one piston member constructed to move within said cylinder, said valve comprising; means con- I structed and arranged to be moved by said piston in the same directions as the latter, said means being constructed to frictionally engage a surface of said piston and to obstruct said aperture when said piston moves in one direction and to frictionally engage said piston and unblock said aperture when said piston movesin another direction opposite to said one direction.

6. The 'valve according to claim 5 wherein said valve means includes a portion thereof which coacts with said cylinder member to limit 'themovement of said valve means in said opposite direction of movement of said piston.

7. The valve according to claim 6 wherein said one direction is the inward stroke direction of said piston and wherein said oppositedirection is the direction of the outward stroke of said piston.

References Cited by the Examiner UNITED STATES PATENTS 452,101 5/91 Ellithorpe 184-6 1,277,541 9/18 Brownback 12341.13 1,327,565 1/20 .MacDonald 1846 1,359,166 11/20 Good 123-41.13 2,420,929 j 5/47 Buffington' 277-205 2,660,493 11/53 Flick 277-205 2,917,269 :12/59 Welker j 251-62 3,029,061 4/62 Hoxworth 251-62- M. CARY NELSON, Primary Examiner.

7 I KARL J. ALBRECHT, Examiner. 

5. A VALVE FOR AN ENGINE WHICH HAS AT LEAST ONE CYLINDER MEMBER THEREIN WITH AN APERTURE IN A WALL THEREOF AND ALSO HAS AT LEAST ONE PISTON MEMBER CONSTRUCTED TO MOVE WITHIN SAID CYLINDER, SAID VALVE COMPRISING: MEANS CONSTRUCTED AND ARRANGED TO BE MOVED BY SAID PISTON IN THE SAME DIRECTIONS AS THE LATTER, SAID MEANS BEING CONSTRUCTED TO FRICTIONALLY ENGAGE A SURFACE OF SAID PISTON AND TO OBSTRUCT SAID APERTURE WHEN SAID PISTON MOVES IN ONE DIRECTION AND TO FRICTIONALLY ENGAGE SAID PISTON AND UNBLOCK SAID APERTURE WHEN SAID PISTON MOVES IN ANOTHER 